PROVING it is possible to have two cakes and eat them both, Audi has strapped an extra turbo onto its 3.0-litre V6 diesel engine to create an A6 sedan that cracks 0-100km/h quicker than a Porsche Boxster but consumes less fuel than a Toyota Corolla.

No matter how impressive, the standing-start acceleration figure does this engine a bit of a disservice as it is the sheer mid-range punch that impresses most, making the decision to overtake a B-double far easier.

Audi expects the TDI Biturbo to account for a quarter of A6 sales, and the same for the A7 Sportback that has also just received the new engine.

But does the new variant really add value and relevance to the A6 range in Australia?

Click the Our Opinion link to find out...